Biological sample storage and preservation is desired as the preserved sample can be used for various applications, such as analyte detection, sensing, forensic and diagnostic applications, genome sequencing, whole-genome amplification, and the like. The sample storage and preservation require sample drying on a substrate.
Some of the currently used devices for preservation of samples on paper substrates are available. For example, a buccal cell sampling device, wherein the sample is dried on a substrate under ambient conditions. The sample drying using such device may be a slow process, particularly at high humidity. Porous or non-porous substrates are commonly used for preservation of biological samples, such as paper cards or membranes. Examples of paper cards or membranes include chemically treated FTA® and FTA®Elute papers (GE Healthcare) for preservation of nucleic acid samples, and the FTA®DMPK cards and 903® cards (GE Healthcare) for preservation of blood samples. The substrates employed a method of absorption and drying of a wet biological sample, such as blood, buccal swabs or macerated tissue disposed on the substrate, however the drying process is time consuming. An incomplete or slow drying affects the stability of the sample and that may generate inconsistent results in subsequent analyses of the preserved samples. The time consuming method of drying a sample limits application of the substrate to use in a lab facility or other time sensitive applications.
A number of portable heat sources, particularly for applications to the heating of food are known. The portable heat sources have a number of disadvantages, including the low efficiency and formation of flammable and/or toxic by-products that may be harmful for biological samples. Chemical heat pads or chemical heaters are also known to evaporate various solvents, however the chemical heaters employ corrosive chemicals, for example, the reaction of sodium hydroxide with hydrochloric acid.
A substrate with a heat source, which is safe during operation, storage and transport, convenient to use and efficient to generate required heat for biological sample drying is highly desirable. Accordingly, there is a need for a method and a device that dries a biological sample in a minimal time without affecting the quality of the sample for subsequent storage and analysis.